Conventional bicycles are traditionally driven by a chain. The chain is connected between a forward sprocket and a rear sprocket. The forward sprocket is connected to the crank. The rider's feet engage the crank for propelling the bicycle forward.
Installation of the chain simply involves use of a master link. The master link allows the chain to be “broken” and reconnected. Consequently, there is no need to open a gap in the bicycle frame to allow the chain to pass though the frame since the chain can be opened using the master link.
Representative of the art is U.S. Pat. No. 4,909,529 which discloses a bicycle having a belt and pulleys in place of the usual chain and sprockets. Each pulley has three (more of less) raceways separated by discs (pulley walls). The discs (pulley walls) have openings that permit the belt to be shifted from one raceway to another raceway. A rotatable arm pivoted to the frame of the bicycle controls the shifting of the belt to the desired raceways. One end of the arm applies lateral pressure to the belt just before it arrives at the pulley associated with the driving pedals of the bicycle, to shift raceways for the driving pulley. Similarly the other end of the arm applies lateral pressure to the belt just before it enters the driven pulley to shift raceways of that pulley. Each end of the arm is biased by a main spring to apply vertical pressure to the belt to maintain it tight.
The ability to use flexible belts on bicycles is desirable since belts are more quiet, clean and efficient than chains. However, since belts are manufactured in a continuous loop which cannot be cut so it can be passed through a frame, it is then necessary to cut or open a gap in the frame itself though which the belt can pass. The gap must be closeable so that the structural integrity of the frame is fully restored for use. The gap must also be reliable and reusable so the belt can be replaced as desired. The frame components affected by this are the drop out, seat stay and the chain stay.
What is needed is a bicycle drop out for installation of a belt through a bicycle frame. The present invention meets this need.